Fuel cells, which generate electric energy through an electrochemical reaction between oxygen and hydrogen, are used in automobiles and portable devices as a clean power source having a high energy conversion efficiency. Because hydrogen is difficult to handle, in a certain type of fuel cell, stored hydrogen is not supplied thereto, but instead, an alcohol or hydrocarbon stored is reacted so that a gas composed mainly of hydrogen is generated, and the generated gas is supplied to the fuel cell. A reaction apparatus is used to generate the gas composed mainly of hydrogen.
A conventional reaction apparatus is disclosed in, for example, Japanese Unexamined Patent Publication JP-A 2004-356003. The reaction apparatus disclosed in JP-A 2004-356003 includes a reforming portion that reforms a material that can produce hydrogen through the decomposition of methanol or the like. In the reforming portion, combustion heat generated by a combustion portion through combustion of fuel is propagated from a heat exchanging portion, such as a metal plate of metal foil, and heats a catalyst provided on one surface of a reaction flow channel. The combustion portion includes a heater that conducts current and heats fuel to combust fuel upon start up.
Another conventional reaction apparatus is disclosed in, for example, Japanese Unexamined Patent Publication JP-A 2005-166283. The reaction apparatus disclosed in JP-A 2005-166283 includes a reformer that can produce hydrogen by reforming an organic compound. The reformer supplies a reformed gas containing reformed hydrogen and carbon monoxide to a CO converter and a CO remover that can cause a reaction at a lower temperature.
In the reaction apparatus disclosed in JP-A 2004-356003, it is shown that the heat exchanging portion is made by forming a metal film onto a substrate by vapor deposition or bonding a metal plane (metal foil) to a substrate. In this manner, when attaching the metal film onto the substrate directly, a difference in coefficient of thermal expansion between the substrate and the metal film is significantly large, so that stress is caused in an interface thereof. As a result, there arises a problem that the metal film and the substrate tend to separate from each other or make a gap therebetween.
Furthermore, in the reaction apparatus disclosed in JP-A 2005-166283, the reformer portion and the CO remover (or CO converter) have different reaction temperatures, and, therefore, it is preferable to suppress thermal conduction between the reformer and the CO remover as much as possible. However, when configuring a reformer, a CO remover, and a connecting pipe for connecting the reformer and the CO remover using a material having low thermal conductivity, a problem arises that the reactors cannot be heated quickly to a uniform temperature. On the other hand, the present inventors have developed a finding that forming a reformer and a carbon monoxide remover using a metal having good thermal conductivity is effective in rapidly heating the reformer and the carbon monoxide remover. In this case, both reactors can be heated rapidly, and the whole of the respective reactors can be heated to a uniform temperature. However, the appropriate reaction temperature of the carbon monoxide remover is usually lower than that of the reformer, so that heat is excessively propagated from the reformer to the carbon monoxide remover and cooling the reformer, or excessively heating the carbon monoxide remover. Accordingly, it is not at all easy to appropriately control reaction temperatures particularly for a small-scale reformer and carbon monoxide remover.